Process for activating cellulose bearing material preparatory to hydrolysis



Patented Oct. 27, 1931 UNITED STATES PATENT OFFICE JOHN PERL, or Los ANGELES, CALIFORNIA, ASSIGNOR r M. M. coRY, or SAN DIEGO, CALIFORNIA PROCESS FOR ACTIVATING CELLULOSE BEARING MATERIAL PREPARATORY 'ro HYDRoLYsIs No Drawing.

My invention relates to a process for ac tivating cellulose bearing materials, preparatory to hydrolysis.

In the.industrial hydrolysis of wood or.

cellulose bearing material into invert sugars, glucose, dextrose, etc., by means of acid catalysts, difliculty is experienced in controlling the yields, and the properties of end products owing to the varying speed or time of the reaction.

The natural cellulose yielding materials represent an organized structure of chemical compounds of the carbohydrate series interpenetrated with cementing substances of non-carbohydrate nature. The fiber structure, which is composed of a highly molecular cellulose complex, is called the tracheid, while the cementing structure is the middle lamella. During treatment with hydrolytic agents, the tracheids take up electrolytes by adsorption. Owing to their colloidal structure, they begin to swell with subsequent gelatinization during the reactive period. Already during the swelling periodthe tracheids begin to separate from the middle lamellae and in due time the reagents will penetrate int-o the inner cells of the tracheids.

The process of hydrolizing cellulosic carbohydrates into monoor poly-saccharides depends largely on this first colloidal adsorption of the electrolytes by the swelling of the surface membrane of the tracheid fibers. When the surface membrane is in such condition that swelling and gelatinization is sluggish or prevented, the chemical reaction is correspondingly sluggish or is stopped at the sur ace, resulting in the deeper cells not being reached by the reagent within a reasonable or practicable length of time.

The cellulose fibers are very susceptible to chemical influences and easily lose their colloidal nature, resulting in decreased ability for adsorbing electrolytes for asubsequent swelling peridd. Even seasoning, atmospheric exposure, heating, or rapid drying will change the outer surface of the,

' tracheid into a colloidally inactive modifica- 59 tion. This can also be described as a shrink- Application filed June 15, 1925.

ing, setting, or hardening of the peripheral Wall into a waterproof film, diificult to wet, inactive, and very resistant to the adsorption of electrolytes.

Such conditions occur during the manufacture of mechanical paper pulp where the Wood is ground on a stone surface. l/Vhen it is desired to subject such ground wood pulp to chemical reactions, like hydrolysis, the surface inactivation caused by the fric- 60 tional heat during mechanical grinding will offer great obstacles for the penetration of chemical reagents, and particularly such reagent catayls.s as are used in hydrolysis. It is known in paper manufacturing that such 5 mechanical wood pulp will give a lower yield of pulp fiber, when subjected to cooking with pulping reagents, than wood disintegrated by other non-heating methods. btill more pronounced is the eiiect of this surface inactivation when such material is subjected to hydrolysis. Such modified surface fihn, which materially resists the action of electrolytes, scientific investigators pronounce to be composed of hydro-cellulose. This inactive surface layer or hydro-cellulose film is soluble in dilute alkali solutions and after Washing off the alkali solvent the fiber is reverted to its original state of adsorbivity.

In the process of hydrolyzing cellulose yielding material into mofioor poly-sacc-harides by exactand controlled reactive conditions, it is quite essential that the condition of the tracheid surface shall be uniform, and 35 readilyv adsorptive; otherwise, rapid conversion into uniformly controlled products and yields would be an impossibility. Also, in this same connection, it might be mentioned that slow or sluggish conversion tends to reduce the ultimate amount of, saccharides obtained, either due to the reagent not reaching all of the deep cells, or on account of the reaction notbeing continued longenough, or due to the fact that under these conditions the reagent is allowed to act on the outer cells so long that the reaction with them is carried farther than desired, and results in undesired or detrimental products; as, in the case 10.

of partial caramelization of the converted saccharides.

The principal object of this invention, therefore, is to prepare or precondition the raw material to be hydrolyzed into such uni; form colloidal reactivity that,-irrespective of the age, seasoning, or the presence of a Small amount of moisture, or the colloidal reactivity of the disintegrated raw material, when reactive conditions (time, temperature and concentration) during hydrolysis are uniformly controlled, a. uniform yield and conversion product or uniform mixture of several conversion products will result at all times and in every case.

Another object of this invention is to prepare or precondition the raw material in respect to colloidal reactivity in several ways or a combination of ways; as,for illustration, the case previously referred to where it is necessary to dissolve or remove with alkali any resistant hydro-cellulose surface from the cellulose fibers previous to activation. 1

With these and other objectsin view, as.

will appear herein, my invention consists of the certain novel method of preconditioning cellulose yielding material, as will be hereinafter described in detail and particularly set forth in the appended claims.

My process is as follows:

During the drying of cellulose yielding raw materials with a current of preheated gases, a reagent is permitted to react on the material, keeping the surface membrane of the material in an activated condition, or the raw material is first mixed with the reagent and then brought to vaporizing temperature and then dried. It will be noted that the principle of this invention is that when proper reagents are mixed with or allowed to act on the raw material, after the raw material has been preheated to vaporizing temperature of its moisture, during the drying process the time of reaction at elevated temperatures is reduced and many of its disadvantages overcome. The degree of preheating to vaporization temperature before adding the reagent will depend on the method employed and may be computed from the respective partial v'apor tensions of water at the prevailmg drying conditions, allowing for the temperature of the reagent to be added and also its reaction effects on the material, and, of course, during drying the temperature will be kept at or above this vaporizing temperature. In case the drying is done with reduced pressure, such as vacuum drying, the raw material is also preheated to a temperature corresponding to the boiling point of water at the given pressure reduction, the reagents admixed with it and subjected to vacuum evaporation.

Sometimes the hydrolysis of cellulose hearing material is not preceded by drying.

Under these conditions, when it is desired to by previous heat, drying, natural or artificial seasoning, or by previous chemical process,

as often happens with seasoning or aged wood in finely divided condition, such as chips, sawdust, etc., it is essential to first remove the hydro-cellulose surface film before reactivation with reagents, which may be done with a weak solution of caustic alkali, subsequent washing and reactivation, as herein described.

As a concrete example of such activation, I would mention the case of finely disintegrating wood for subsequent hydrolysis by means of grinding on stones or being struck or pounded by metal dogs or hammers or other mechanical means, providing thorough disintegration, and which cause considerable frictional heat, which heat is taken up by the wood, and being exposed to the air and moisture, its surface will'be converted into an inactive hydrocellulose film. This mechanical wood pulp is reactivated by my process as follows:

The pulp is moistened with water, then subjected to washing with a warm solution of weak caustic soda in a pulp heater or a rotary mixer, then drained, then washed with clean water and a weak solution of sulphuric acid added until a slight acidity is indicated which weak solution of acid in excess of enough to neutralize the absorbed alkali and natural wood bases is for the purpose of activation. The pulp so acidified is then warmed in an agitating tank until the adsorbed alkali and natural wood bases are neutralized leaving the excess acid for actiacid are not as detrimental toan eflicient fermentation process as are the chlorides, hydrofiuorides or salts of organic acids. However, in case the hydrolyzed products are to be used for other purposes than fermentation processes, any other acid may be used for this neutralization step, unless the. salts so formed will be harmful as a food (product.

The reagents employe for such surface activation may be mineral acids, such as hydrochloric acid, nitric acid, sulphurous acid, sulphuric acid; or organic fatty acids such as ormic or acetic; oroxalic acid; or the alkali salts of organic fatty acids, such as salts of formic acid, acetic acid; or salts of oxalic acid or a mixture or any or all of these acids or salts. 0

It will be noted that the process may be made more economical by the use of cheaper admixture with mineral acids as activators.

Though I have described a certain process and modifications, I do not wish to be limited to the processes set forth nor to the modifications, but desire to include in the scope of my invention the processes substantially as set forth in the appended claims.

Having thus described my invention, what I claim as new and desire to secure by Letters Patent is:

1. In the art of hydrolysis of cellulose bearing materials, before hydrolysis, the step of activating such materials comprising the subjecting of said materials to the action of organic fatty acids in amounts insufficient to hydrolize.

2. In the art of hydrolysis of cellulose moisture bearing materials, before they are .dry' and before hydrolysis, the step of activating such materials comprising the subjecting of said materials to the action of organic fatty acids in amounts insufiicient to hydrolize. I

3. In the art of hydrolysis of cellulose moisture bearing materials,before hydrolysis and before they are dry, the step of activating such materials comprising the subjecting of saidmaterials to the action of tar-free pyroligneous acid in amounts insufficient to hydrolize.

4. In the art of hydrolysis of cellulose moisture bearing materials, before hydrolysis and before they are dry, the step of activating such materials comprising the subjecting of said materials to the action of pyroligneous acid in amounts insufficient to hydrolize.

5. In the art of hydrolysis of cellulose moisture bearing materials, before hydrolysis andbefore they are dry, the step of activating such materials comprising the subjecting of said materials to the action of small amounts of organicfatty acids of the fatty acid series and insuflicient in amount to,

hydrolize.

6. In the art of hydrolysisv of cellulose bearing materials. before hydrolysis and before they are dryoin a current of preheated gases, the ste of activating such materials comprising t e subjecting of said cellul ose pre-heated gases, the step of activating such a materials comprising the subjecting of said cellulose bearing materials to the action of oxalic acid in amounts insuflicient to hydroliz e.

, 9. In the art of hydrolysis of cellulose moisture bearing materials, before hydrolysis and while being dried in a current of preheated gases, the step of activating such materials comprising the subjecting of said cellulose bearing materials, before they are dry,

to the action of small amounts oforganic acids of the fatty acid series in amounts insuflicient to hydrolize.

10. In the art of hydrolysis of cellulose moisture bearing materials, before they are dry and before hydrolysis, the step of activating such materials comprising the subjecting of'said materials to the action of small amounts of mineral and organic fatty acids in amounts insuflicient to hydrolize.

11. In the art of hydrolysis of cellulose moisture bearing materials, durin drying and before hydrolysis, the step 0 activating such, materials comprising the subjecting of said materials to the actionof small amounts of mineral and organic fatty acids in amounts insufficient to hydrolize.

12. In the art of hydrolysis of cellulose bearing materials, before hydrolysis, the step of activating such materials comprising the subjecting of said materials to the action of tar-free pyroligneous acid in amounts insufficient to hydrolize. l

13. In the art of hydrolysis of cellulose bearing materials, before hydrolysis, "the step of activating such materials comprising the elimination of the inactive surface film of said materials by Washing with dilute alkali solution, then rinsing, then neutralizin any remaining alkali by the action of aci and then drying.

14. In the art of hydrolysis of cellulose bearing materials, before hydrolysis, the step of activating such materials comprising the elimination of the inactive surface film of said materials by washing with dilute alkali solution, then rinsing. then neutralizing any alkali, and activating, by subjecting to the action of acid in amounts insufficient to elimination of the inactive surface of activating such materials comprising 'filmth;

said materials by washing with dilute alkali solution, then neutralizing any remaining alkali by the action of acid, and then drying.

16. In the art of hydrolysis of cellulose bearing materials, before hydrolysis, the step of activating such materials comprising the elimination of the inactive surface film of said materials by washing with dilute alkali solution, then neutralizing any alkali, andactivating. by sub'ecting to the action of acid in amounts ms cient to hydrolize.

In testimony whereof, I have hereunto set my hand at Los An 8th day of June, 1925.

- JOHN PERL.

geles, California, 

